Method for the roll-forming of profiles and a structural part produced thereby

ABSTRACT

A method for the roll-forming of profiles or structural parts from semifinished sheet-like products, in particular from metallic materials, in particular from steel sheet or aluminum. For this, the semifinished sheet-like product is adjusted in its temperature, the adjustment of the temperature taking place locally, in particular in forming regions of the semifinished product that are intended to undergo a forming operation. Furthermore, a component is preferably produced by using this method, in particular a structural part for a seat structure of a motor vehicle, in particular a vehicle seat rail that can be adjusted forwards and backwards to adjust the seat, and to a roll-forming device for carrying out the method.

The invention relates to a method for the roll-forming of profiles or structural parts from semifinished sheet-like products, in particular from metallic materials, in particular from steel sheet or aluminum. Furthermore, the invention relates to a component preferably produced with the application of this method, in particular to a structural part for a seat structure of a motor vehicle, and to a roll-forming device for implementing the method.

Such profiles or structural parts require particular strengths of the material used so that the mostly structural components have an adequate load capacity. At the same time, however, the least-possible use of material is required, for example in order to achieve a favourable cost structure in manufacture. However, with known roll-forming processes it is unlikely that further materials savings can be achieved, because harder materials, in particular high-strength materials, can only be roll-formed with certain limitations and, with lesser wall thicknesses of the material, increased elastic recovery, during manufacture or directly following manufacture, occurs. For this reason, high-strength steels with tensile strengths of up to 800 MPa and a wall thickness of at least 1.6 mm are frequently used in manufacture. Semifinished products with lesser wall thicknesses and/or greater tensile strengths have hitherto not been feasible, at least in structural parts for seat structures of motor vehicles, in particular for vehicle seat rails.

It is thus the object of the invention to improve the deformability of a semifinished product in the regions intended to undergo a forming operation and to minimise the elastic recovery behaviour of a finished component.

In terms of the method, this object is met by the characteristics of claim 1. A component produced with the method is defined by means of the characteristics of claim 8, and a roll-forming device for implementing the method is defined by means of the characteristics of claim 12. Improvements and advantageous embodiments are stated in the respective subordinate claims.

In such a method, according to the invention it is provided that the semifinished sheet-like product is temperature-controlled for the roll-forming process, wherein temperature-control takes place locally, in particular in forming regions of the semifinished product, which forming regions are intended to undergo a forming operation. Temperature-controlling can involve heating and/or cooling, and preferably takes place before or during forming the semifinished product. Profiles or structural components processed with the use of this method then have a higher load capacity than those that were not temperature-controlled.

Depending on the shape of the profile or component to be manufactured, the roll-forming process takes place in a predetermined forming sequence. In this context the term “forming sequence” designates the sequence in which the forming regions are to be processed, i.e. formed, wherein the forming sequence results from the profile or structural part to be produced, and from its radii. Each profile manufactured by roll-forming thus comprises a determined forming sequence during the roll-forming process. In order to achieve timely linking, which is as direct as possible, of rolling, or forming and temperature-controlling, it is provided for the forming regions to be temperature-controlled one after the other in the forming sequence of the roll-forming process. In this manner it is possible, on the one hand, to reduce the energy input required for the process, and, on the other hand, to reduce the load acting on the semifinished product intended to undergo a forming operation, or on the finished component, during manufacture.

In this process, local heating preferably takes place on strip-shaped forming regions of the semifinished product, which strip-shaped forming regions are aligned in the direction of roll-forming so that the forming regions subjected to force and deformed during forming or processing are temperature-controlled, in particular heated.

Depending on the implementation or design of the method, advantageously either inductive heating is applied, or an energy input takes place by means of laser radiation. Both method-related implementations provide the option of heating the semifinished product, which is intended to undergo a forming operation, at specific points and thus in a targeted manner in the forming regions. In a preferred embodiment, laser radiation takes place by means of a fibre laser.

It is also possible for the semifinished product to be hardened after forming, i.e. quenched with the use of a coolant, for example an oil bath or the like. A component produced in this manner can comprise still higher and thus improved strength, in particular in previously locally-heated forming regions or radius regions. In this process, these locally heated forming regions or radius regions can have been heated before, during or after forming or roll-forming.

Moreover, this results in a further application option of the method, which application option consists of producing the component or structural part to be manufactured from the usually used softer material, which material as a rule is thus more economical, in particular from a somewhat softer steel, which steel is hardened by subsequent quenching. Moreover, local temperature-controlling, in particular local heating, can take place in combination with quenching or hardening following roll-forming. In this manner it is then possible, for example, to improve the load capacity of softer materials, which are easier to form, for example manganese-boron steel, and consequently profiles manufactured from these materials, too, can be further optimised.

In a component, in particular a structural component for a seat structure of a motor vehicle, with sheet-like sections, which are angled relative to each other, that are interconnected by way of at least one forming region designed as a radius, according to the invention it is provided that the forming region has been subjected to a temperature-control process that alters the materials characteristics, and comprises a change in the microstructure as a result of the temperature-control process. Thus the forming regions differ, in terms of their materials structure, from the sheet-like sections and also from other components that were not temperature-controlled and that were processed by means of roll-forming, while however comprising equal or higher strength than the aforesaid.

In particular, the component is manufactured from high-strength steel or from high-strength aluminum whose strength is higher than could otherwise typically be processed in roll-forming methods or roll-forming processes, in particular 1,000 MPa or more, or 1,200 MPa or more, in particular for components made from steel. The component manufactured according to the invention can then preferably comprise wall thicknesses of a 1.5 mm or even 1.4 mm or 1.3 mm or less in each case.

Such components or profiles, manufactured with the use of the method described, are predominantly provided as load-bearing structural components, wherein in a preferred embodiment the component is a vehicle seat rail that can be adjusted forwards and backwards to adjust the seat.

In a roll-forming device suitable for implementing the method, the object according to the patent is met in that various means for temperature-controlling a semifinished product intended to undergo a forming operation are provided. In particular, for the purpose of heating, inductive heating devices and/or lasers, in particular fibre lasers, are provided. For cooling it is possible, for example, to use Peltier elements. In this arrangement the respective means for temperature-controlling can advantageously be exchanged with roller sets of the roll-forming device so that optimal arrangements for various applications are ensured, and various components can be manufactured on a roll-forming device.

The roll-forming method used in this invention is also known as profile rolling, and is, for example, described in DIN 8586, whose content is herewith incorporated in the subject of this application by reference to the aforesaid.

In the figures the invention is further explained with reference to a preferred exemplary embodiment. The following are shown:

FIG. 1: a basic cross section of a component manufactured by means of roll-forming.

FIG. 2: development of the cross section of the component of FIG. 1.

The component 1 shown in FIG. 1 is profiled and typically is manufactured by means of roll-forming. This component 1 comprises several sheet-like sections 3 that have arisen, essentially unchanged, from a semifinished sheet-like product. The sheet-like sections 3 are interconnected in radial regions of the component 1 by means of forming regions 4 a, 4 b, 4 c, 4 d, shown hatched, that are formed during the roll-forming process. In particular in the forming of high-strength steels, in particular with Rm>800 MPa, these forming regions 4 a, 4 b, 4 c, 4 d pose great problems in terms of formability, above all during the formation of tight radii.

FIG. 2 shows a basic development 2 of the cross section of component 1. As is the case in FIG. 1, the forming regions 4 a, 4 b, 4 c, 4 d are shown hatched, are delimited by corresponding lines, and in each case extend in the direction of roll-forming. When moving through a roll-forming device or during roll-forming, these forming regions 4 a, 4 b, 4 c, 4 d are temperature-controlled, in other words heated or cooled. By locally heating or cooling, the materials characteristics can be adjusted according to requirements, and consequently the component 1 comprises a changed microstructure in the forming regions or radial regions. 

1. A method for the roll-forming of profiles or structural parts from semifinished sheet-like products, the method comprising: temperature adjusting the semifinished sheet-like product for the roll-forming process, wherein temperature adjustment takes place locally forming regions of the semifinished product that are intended to undergo a forming operation.
 2. The method according to claim 1, wherein temperature adjustment takes place prior to or during forming of the semifinished product.
 3. The method according to claim 1, wherein the forming regions are temperature-adjusted one after the other in the forming sequence of the roll-forming process.
 4. The method according to claim 1, wherein strip-shaped forming regions of the semifinished product are heated, which forming regions are aligned in the direction of roll-forming.
 5. The method according to claim 1, wherein heating takes place inductively.
 6. The method according to claim 1, wherein heating takes place by means of laser radiation.
 7. The method according to claim 1, wherein after the forming process the semifinished product is hardened.
 8. A component comprising: sheet-like sections, which arc angled relative to each other, that are interconnected by way of at least one forming region that is a radius, wherein the forming region has been subjected to a temperature-control process that alters the materials characteristics, and comprises a change in the microstructure as a result of the temperature-control process.
 9. The component according to claim 8, wherein the component is manufactured from high-strength steel or from high-strength aluminum.
 10. The component according to claim 8, wherein the component comprises wall thicknesses of a maximum of 1.5 mm, and a strength of 1,000 MPa or greater.
 11. The component according to claim 8, wherein the component is a vehicle seat rail that can be adjusted forwards and backwards to adjust the seat.
 12. A roll-forming device for implementing the method according to claim 1, wherein various means for temperature-controlling a semifinished product intended to undergo a forming operation are provided.
 13. The roll-forming device according to claim 12, wherein the roll-forming device comprises inductive heating devices and/or lasers.
 14. The roll-forming device according to claim 12, comprising Peltier elements. 